(diff-buffer-with-file): Check whether associated file exists.

Display message for 1 second.  Always return nil.

2 files changed, 25 insertions, 14 deletions

diff --git a/lisp/ChangeLog b/lisp/ChangeLog
index c56b9536f90..ccda6c1344e 100644
--- a/lisp/ChangeLog
+++ b/lisp/ChangeLog
@@ -1,3 +1,8 @@
+2002-09-13  Markus Rost  <rost@math.ohio-state.edu>
+
+        * files.el (diff-buffer-with-file): Check whether associated file
+        exists.  Display message for 1 second.  Always return nil.
+
 2002-09-13  Stefan Monnier  <monnier@cs.yale.edu>
 
         * derived.el (define-derived-mode): Properly ignore unknown args.
@@ -81,8 +86,8 @@
 
 2002-09-11  Vinicius Jose Latorre  <vinicius@cpqd.com.br>
 
-        * ps-print.el: Adjust ps-print-color-p, ps-default-fg and ps-default-bg
-        setting.
+        * ps-print.el: Adjust ps-print-color-p, ps-default-fg and
+        ps-default-bg setting.
         (ps-print-version): New version number (6.5.7).
         (ps-mark-active-p): New fun.
         (ps-print-preprint-region): Adjust code.
diff --git a/lisp/files.el b/lisp/files.el
index 31d2b8762fa..020249dbf23 100644
--- a/lisp/files.el
+++ b/lisp/files.el
@@ -2999,18 +2999,24 @@ After saving the buffer, this function runs `after-save-hook'."
 This requires the external program `diff' to be in your `exec-path'."
   (interactive "bBuffer: ")
   (with-current-buffer (get-buffer (or buffer (current-buffer)))
-    (if (null buffer-file-name)
-        (message "Buffer %s has no associated file" (buffer-name))
-      (let ((tempfile (make-temp-file "buffer-content-")))
-        (unwind-protect
-            (save-restriction
-              (widen)
-              (write-region (point-min) (point-max) tempfile nil 'nomessage)
-              (diff buffer-file-name tempfile nil t)
-              (sit-for 0))
-          (when (file-exists-p tempfile)
-            (delete-file tempfile)))
-        nil))))
+    (if (and buffer-file-name
+             (file-exists-p buffer-file-name))
+        (let ((tempfile (make-temp-file "buffer-content-")))
+          (unwind-protect
+              (save-restriction
+                (widen)
+                (write-region (point-min) (point-max) tempfile nil 'nomessage)
+                (diff buffer-file-name tempfile nil t)
+                (sit-for 0))
+            (when (file-exists-p tempfile)
+              (delete-file tempfile))))
+      (message "Buffer %s has no associated file on disc" (buffer-name))
+      ;; Display that message for 1 second so that user can read it
+      ;; in the minibuffer.
+      (sit-for 1)))
+  ;; return always nil, so that save-buffers-kill-emacs will not move
+  ;; over to the next unsaved buffer when calling `d'.
+  nil)
 
 (defvar save-some-buffers-action-alist
   '((?\C-r